The identification and administration of an effective antimicrobial agent is of the utmost importance in clinical and point-of-care patient settings. Specifically, with the emergence of multi-drug resistant bacterial strains, such as methicillin-resistant Staphylococcus aureus (MRSA) and multiply drug resistant tuberculosis (XDR-TB), identifying the most effective antibiotic and administering it to the patient at concentrations that will kill or inhibit bacterial growth without undermining the patient's health is important.
Currently, the assessment of antimicrobial susceptibility relies on the isolation of the microorganism, followed by an attempt to grow the pathogen in the presence of various antibiotic agents and different concentrations thereof. A major problem with this approach is that it requires at least 24 hours in order to provide qualitative and quantitative information associated with the effectiveness of the antibitiotic. In the meantime, even though physicians will institute treatment on clinical grounds and without waiting for the lab results, the patient might face severe complications and worsening of his/her pathological condition due to growth and pathogenesis induced by the microorganism and inability of the immune system to respond in an effective way. As mentioned before, typically, physicians caring for the hospitalized patient must start antibiotic treatment based only on experience and clinical hunches, since the results of in vitro antibiotic susceptibility tests will not be available for 48-72 hours after initial cultures are taken.
Therefore, the need of fast and accurate antimicrobial susceptibility assessment modalities remains, even in this day of modern medical advances. Additionally, apart from clinical and point-of-care diagnostics, the pharmaceutical industry is under pressure to continue development of novel, sensitive and rapid antimicrobial susceptibility assays. Hence, having methods to facilitate high-throughput screening of candidate antibiotics, while using small sample volumes, could reduce the costs associated with drug development and expedite the drug development process.